1. Field of the Invention
The present invention relates to an oscillator and a semiconductor device.
2. Description of the Related Art
In recent years, reduction in power consumption is required in products made with ecological sensitivity or electronic devices such as portable devices. With this, reduction in current consumption is required of each of the elements (an oscillator and a semiconductor device) which control these electronic devices. This requirement also needs reduction in power consumption in a system operation, and how small the current consumption in the standby state is made leads to product differentiation in the system. For this purpose, it is necessary to decrease waiting time for stabilization of oscillation of a system clock (oscillator), which becomes always necessary, as much as possible and to perform a constant process (count of a clock and the like) early, in the state transition to the normal operation state from the above described standby state. Attention is paid to a method for decreasing average current consumption by transition to the standby state.
Besides, Japanese Patent Application Laid-open No. 6-338751 discloses a crystal resonator which shortens rise time by decreasing overshoot of oscillation frequency at a time of rise of the oscillator.